Supplementary Table 1: The sentinel hospital IDs and locations. There are 23 hospital sites that perform laboratory confirmation of V. cholerae in Bangladesh.
| 1 |
District Hospital Norshingdi |
Dhaka |
district |
| 2 |
Adhunik Sadar Hospital Habiganj |
Sylhet |
district |
| 3 |
District Sadar Hospital Cox’s Bazar |
Chittagong |
district |
| 4 |
Adhunik Sadar Hospital Naogaon |
Rajshahi |
district |
| 5 |
General Hospital Patuakhali |
Barisal |
tertiary |
| 6 |
Adhunik Sadar Hospital Thakurgaon |
Rangpur |
district |
| 7 |
District Sadar Hospital Satkhira |
Khulna |
district |
| 8 |
Dhaka Medical College Dhaka |
Dhaka |
tertiary |
| 9 |
Uttara Adhunik Medical College Hospital |
Dhaka |
tertiary |
| 10 |
Bangladesh Institute of Tropical and Infectious Diseases Chittagong |
Chittagong |
tertiary |
| 11 |
General Hospital Tangail |
Dhaka |
district |
| 12 |
General Hospital Narayanganj |
Dhaka |
district |
| 13 |
Sadar Hospital Chuadanga |
Khulna |
district |
| 14 |
General Hospital Meherpur |
Khulna |
district |
| 15 |
General Hospital Comilla |
Chittagong |
district |
| 16 |
Upazila Health Complex Chaugachha Jesssore |
Khulna |
subdistrict |
| 17 |
General Hospital Kusthia |
Khulna |
district |
| 18 |
Upazila Health Complex Madan |
Mymensingh |
subdistrict |
| 19 |
Upazila Health Complex Chhatak Sunamganj |
Sylhet |
subdistrict |
| 20 |
Upazila Health Complex Mathbariya |
Barisal |
subdistrict |
| 21 |
Upazila Health Complex Bakerganj |
Barisal |
subdistrict |
| 22 |
Health Complex Shibganj |
Rajshahi |
subdistrict |
| 23 |
icddr,b Cholera Hospital |
Dhaka |
icddrb |
Supplementary Table 2: Population living in the cholera surveillance zone.
| 10-20-30-30 |
50888584 |
0.3129697 |
Figure 1: A. Median risk of V. cholerae seroincidence relative to a population-weighted mean by 5 km x 5 km grid cell. These relative risk estimates are bounded such that RRs above and below 2 and -2 were plotted as the values 2 and -2, repsectively. The black marks indicate sentinel hospital locations. B. Map of the uncertainty of the seroincidence estimates measured by entropy by 5 km x 5 km grid cell. The black marks indicate the serosurvey sites from the cross-sectional survey conducted in 2015. C. Cholera risk map as categorized by the risk of seroincidence relative to a population-weighted mean by 5 km x 5 km grid cell. The map illustrates grid cells of High-Moderate-Low risk and the which grid cells are captured by the cholera surveillance zone ( 10-20-30-30km for subdistrict, district, and tertiary care, and icddr,b hospitals), indicated by the transparent buffers.

Figure 2: Cholera greyspots. A. The 5 km x 5 km grid cells that are colored are cells covered in the cholera surveillance zone. The greyed out grid cells are areas not captured by the national surveillance system. B. The 5 km x 5 km grid cells that are colored are cells where we have reasonably confident seroincidence estimates (entropy < 0.3) or that are in the cholera surveillance zone. Grid cells in grey are greyspots, locations where we have almost no cholera information.

Supplementary Figure 1: A. The relative seroincidence risk within cholera surveillance zones (for subdistrict, district, and tertiary care, and icddr,b hospitals). B. High-certainty grid cells based on the measure of entropy with the cholera surveillance zones overlayed.

Supplementary Table 3: Population living in each risk category. The population living in high, moderate, and low risk areas according to relative seroincidence risk across Bangladesh.
| High |
9207436 |
| Moderate |
98962248 |
| Low |
54429387 |
Table 1: Part 1. Number and percent infections that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals in Bangladesh. Part 2. Number and percent infections that may be captured in cholera surveillance zones, categorized by relative risk. The infections in surveillance zone represents the percentage of infected people in high-moderate-low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high-moderate-low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections that may be captured in Bangladesh, categorized by relative risk. The captured at-risk population represents the percentage of high-moderate-low risk populations captured by the cholera surveillance zone out of all high-moderate-low risk populations in Bangladesh. The captured infections represents the percentage of infections in high-moderate-low risk grid cells among all infections in high-moderate-low risk grid cells across Bangladesh.
| 10-20-30-30 |
50,888,584 |
6,802,113 |
13.4 |
28.7 |
| 10-20-30-30 |
High |
817,295 |
12.0 |
3,113,395 |
6.1 |
| 10-20-30-30 |
Moderate |
3,070,442 |
45.1 |
19,839,091 |
39.0 |
| 10-20-30-30 |
Low |
2,914,375 |
42.8 |
27,936,098 |
54.9 |
| 10-20-30-30 |
High |
3,113,395 |
817,295 |
33.8 |
32.2 |
| 10-20-30-30 |
Moderate |
19,839,091 |
3,070,442 |
20.0 |
20.3 |
| 10-20-30-30 |
Low |
27,936,098 |
2,914,375 |
51.3 |
48.2 |
Supplementary Figure 2: A. Median number of estimated V. cholerae infections per grid cell in the previous year. The black marks indicate sentinel hospital locations. B. Cholera risk map as categorized by the estimated number of V. cholerae infections by 5 km x 5 km grid cell. The black marks indicate sentinel hospital locations and transparent buffers overlayed represent the cholera surveillance zone.

Supplementary Table 4: Population living in each risk category. The population living in high, moderate, and low risk areas according to the number of infections across Bangladesh.
| High |
98723766 |
| Moderate |
54850878 |
| Low |
9024426 |
Table 2: Part 1. Number and percent infections that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals in Bangladesh. Part 2. Number and percent infections that may be captured in cholera surveillance zones, categorized by the number of infections. The infections in surveillance zone represents the percentage of infected people in high/moderate/low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high/moderate/low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections that may be captured in Bangladesh, categorized by the number of individuals infected with V. cholerae . The captured at-risk population represents the percentage of high/moderate/low risk populations captured by the cholera surveillance zone out of all high/moderate/low risk populations in Bangladesh. The captured infections represents the percentage of infections in high/moderate/low risk grid cells among all infections in high/moderate/low risk grid cells across Bangladesh.
| 10-20-30-30 |
50,888,584 |
6,802,113 |
13.4 |
28.7 |
| 10-20-30-30 |
High |
5,084,430 |
74.7 |
38,491,888 |
75.6 |
| 10-20-30-30 |
Moderate |
1,556,279 |
22.9 |
11,266,842 |
22.1 |
| 10-20-30-30 |
Low |
161,404 |
2.4 |
1,129,854 |
2.2 |
| 10-20-30-30 |
High |
38,491,888 |
5,084,430 |
39.0 |
34.9 |
| 10-20-30-30 |
Moderate |
11,266,842 |
1,556,279 |
20.5 |
19.9 |
| 10-20-30-30 |
Low |
1,129,854 |
161,404 |
12.5 |
12.3 |
Figure 3: A. The overall percentage of the population living in high-moderate-low risk areas as defined by relative seroincidence risk and absolute number of infections risk measures. B. Bar plot of the percentage of the population in the cholera surveillance zone and percentage of V. cholerae infections in the cholera surveillance zone across Bangladesh and in high-moderate-low risk areas using the relative seroincidence risk and absolute number of infections as measures of risk.

Supplementary Table 5: A. Population living in high certainty areas in the cholera surveillance zone. B. The population living in high, moderate, and low risk areas according to the number of infections across Bangladesh living in areas of high certainty per the entropy threshold of relative seroincidence risk.
| 10-20-30-30 |
22841377 |
0.1404767 |
| High |
0 |
| Moderate |
5292801 |
| Low |
35316745 |
Table 3: Part 1. Number and percent infections in grid cells of high certainty that may be captured in cholera surveillance zones. The percent infected represents the percentage of infected individuals captured within the cholera surveillance zone out of all infected individuals living in areas of high predictive certainty in Bangladesh. Part 2. Number and percent infections in areas of high certainty that may be captured in cholera surveillance zones, categorized by relative risk. The infections in surveillance zone represents the percentage of infected people in high-moderate-low risk grid cells among all infections within the cholera surveillance zone. The population in surveillance zone represents the percentage of people living in high-moderate-low risk grid cells among all people within the cholera surveillance zone. The distribution should across risk categories should sum to 100% for each set of buffer sizes. Part 3. Number and percent infections with high predictive certainty that may be captured in Bangladesh, categorized by relative risk. The captured at-risk population represents the percentage of high-moderate-low risk populations captured by the cholera surveillance zone out of all high-moderate-low risk populations in Bangladesh. The captured infections represents the percentage of infections in high-moderate-low risk grid cells among all infections in high-moderate-low risk grid cells across Bangladesh.
| 10-20-30-30 |
22,841,377 |
2,285,990 |
10 |
52.5 |
| 10-20-30-30 |
Moderate |
161,827 |
7.1 |
1,133,109 |
5 |
| 10-20-30-30 |
Low |
2,124,163 |
92.9 |
21,708,268 |
95 |
| 10-20-30-30 |
Moderate |
1,133,109 |
161,827 |
21.4 |
20.9 |
| 10-20-30-30 |
Low |
21,708,268 |
2,124,163 |
61.5 |
59.4 |
Table 4: A. The population not captured in the surveillance greyspots (cholera surveillance zone). B. The population not captured in the cholera surveillance zone or in areas where we have high certainty of our estimates of relative seroincidence risk. This is also referred to as information greyspots.
| Surveillance greyspot |
111,710,486 |
68.7 |
| Information greyspot |
98,954,591 |
60.9 |